A 77 year old man with asthma and renal impairment

A 77 year old man presented after a collapse at home with a three week history of dyspnoea, malaise, and myalgia. He reported a 10 year history of hypertension, and that he had undergone a nasal polypectomy seven years earlier and had recently been diagnosed as having asthma. Prescribed drugs included candesartan 4 mg daily, enalapril 20 mg daily, beclometasone dipropionate 200 µg twice daily, and salbutamol as needed. He had not recently changed his drugs or used non-steroidal anti-inflammatory agents or herbal remedies. On examination his blood pressure was 156/88 mm Hg; temperature was 36.8°C; and he had generalised polyphonic wheeze, raised jugular venous pressure (5 cm above the sternal angle), and mild bilateral ankle oedema.

Blood tests showed impaired renal function, with creatinine 691 µmol/L (reference range 60-110), urea 46.2 mmol/L (3.0-6.2), compared with creatinine 102 µmol/L and urea 3.0 mmol/L two months earlier. Other results showed haemoglobin 99 g/L (135-180), mean corpuscular volume 89.9 fL (78-100), white cell count 11.52×10⁹/L (4.0-11.0), neutrophils 9.38×10⁹/L (2.0-7.5 x10⁹/L; 81.4%, ), lymphocytes 0.37×10⁹/L (1.0-4.5; 3.2%), monocytes 0.29×10⁹/L (range 0.2-0.8; 2.5%), eosinophils 1.46×10⁹/L (0.04-0.4; 12.7%), basophils 0.00×10⁹/L (<0.1; 0%), platelets 228×10⁹/L (150-400), C reactive protein 857.16 nmol/L (<47.62), and erythrocyte sedimentation rate 115 mm in the first hour (<30).

No paraprotein was detected on serum or urine electrophoresis. Serology was negative for hepatitis B, hepatitis C, and HIV. Urine was positive for protein (urine protein:creatinine ratio 170 mg/mmol, <30), and blood (3+ on dipstick testing). A plain chest film showed clear lung fields and normal cardiac outline. Normal sized, unobstructed kidneys with preserved corticomedullary differentiation were seen on renal tract ultrasound.

He was started on haemodialysis before further investigations to establish a diagnosis.